十六进制到二进制和二进制操作的麻烦

Question

这里是瘦身：我正在拼凑一些将 EUI64 转换回 MAC 地址的代码。从逻辑上讲，这很简单，我认为代码也不会是什么大问题，但我遇到了一些麻烦。

旁注：我对 Javascript 的经验很少

到目前为止，我的问题是：

• 无法告诉 Javascript 将数字定义为十六进制数
• 转换后无法更改数字中的特定二进制

我知道在 Javascript 中，十六进制是通过在数字前添加 0x 来定义的，但是当我尝试对变量执行此操作时，它似乎并不喜欢，并且应用 toString(16) 似乎并没有改变它全部。

继续是我的代码。我承认这是错误的（这就是我在这里的原因），并且我认为展示我所处的位置会很好（尽管我尝试过的很多东西都没有展示）。

eui64toMac=function (eui64)
{
  console.log("EUI64: " + eui64);
  console.log("EUI64 as Hex: " + eui64.toString(16));

  console.log("Isolating and converting first two numbers of EUI64 to Binary.");
  
  convert=(eui64.slice(0, 2));
  console.log("First two of EUI64: " + convert);
  console.log("First two of EUI64 as Hex: " + convert.toString(16));
  convert=(convert >>> 0).toString(2);
  console.log("First two of EUI64 (Binary): " + convert);
  
  console.log("First binary bit: " + convert[0]);
  console.log("Attempt at changing the 1st binary to a 0.");
  // Attempt at changing the 1st binary to a 0 (with no luck)
  var num = 0;
  convert[0] = num;
  console.log("Third binary in sequence change attempt: " + convert[0]);
  
  console.log("Converted number after conversion: " + convert);
    
    return eui64;
}

eui64toMac("92152BFFFEE49B60");

输出：

☁️ "Running fiddle"
"EUI64: 92152BFFFEE49B60"
"EUI64 as Hex: 92152BFFFEE49B60"
"Isolating and converting first two numbers of EUI64 to Binary."
"First two of EUI64: 92"
"First two of EUI64 as Hex: 92"
"First two of EUI64 (Binary): 1011100"
"First binary bit: 1"
"Attempt at changing the 1st binary to a 0."
"Third binary in sequence change attempt: 1"
"Converted number after conversion: 1011100"

对运行代码感兴趣的朋友：https://jsfiddle.net/

Answer 1

根据 eui64 定义，在我看来，您只需删除 FFFE 部分（切片 6,10）即可转换回 mac 地址。

eui64 = "92152BFFFEE49B60"
macaddress = eui64.slice(0,6) + eui64.slice(10,14)
=> "92152BE49B"
lastByte = eui64.slice(14,16)
=> "60"
flip7thBit = parseInt("0x"+lastByte) ^ 128
=> "E0"
macaddressCompleted = macaddress + flip7thBit.toString(16).toUpperCase();
=> "92152BE49BE0"

^ 128 表示xor 128，它有效地翻转了第 7 位。 （2 次方 7 = 128）